Technical: This project addresses reversible crystalline to amorphous phase transition phenomena in self assembled Ge-Sb-Te nanowire (NW) materials at sub-lithographic length scales. The approach focuses on synthesis and characterization of complex, well defined Ge-Sb-Te NWs with control over composition and dimension for investigating fundamental phase switching properties, and assembly of prototype memory elements. Components of the approach include: 1) Development of pulsed laser deposition (PLD) growth technique to synthesize complex ternary Ge-Sb-Te NWs with precise control over NW chemical composition and diameters. 2) Characterization of structural and chemical composition of NWs with electron microscopy (SEM, TEM). 3) Investigation of electric field induced phase switching behavior and its dependence on chemical composition and size (diameter) of NWs. Study of the influence of size on thermodynamic parameters and its affect on phase transition mechanism in NWs. 4) Insitu TEM analysis of structural transformations in Ge-Sb-Te NWs as a function of applied current pulses. Size and chemical composition dependent study of amorphization and recrystallization mechanism in NWs. 5) Fabrication of novel NW memory devices based on insights obtained from the experiments described above.
The project addresses basic research issues in a topical area of electronic/photonic materials science with high technological relevance. Research and educational activities will be integrated by the involvement of undergraduates in the research program, incorporating new research results in a teaching module, and training high school and college teachers from the Philadelphia district with student population from minority and underrepresented sections.
